The term “wear parts” refers to parts, such as of mechanical assemblies, that experience repetitive movements, repeated relative engagement with other parts, and/or otherwise generally undergo processes that require the wear parts to be replaced after a period of time. Examples of wear parts may include such illustrative, non-exclusive examples as fasteners, bushings, bearing carriers, sleeves, and pins. In the aerospace industry, for example, wear parts may include parts associated with landing gear systems, flap and actuator systems, or any other systems that include parts that typically require replacement over time. Aircraft, automobiles, spacecraft, trains, machine tools, robots, manufacturing machines, drilling equipment, pumping equipment, energy generation equipment, vibration absorption equipment, and many, many other mechanical systems also utilize wear parts that require replacement.
Wear parts, or at least wear surfaces of wear parts, often are coated, or at least partially coated, with chrome plating as a hard, protective layer to extend the usable life of the wear parts. Chrome plating used on wear parts additionally or alternatively may be referred to as hard chrome, industrial chrome, and/or engineered chrome. Chrome plating used on wear parts typically has a thickness in the range of approximately 1-5 mils, which may be referred to as standard chrome plating. Sometimes, chrome plating with a thickness in the range of approximately 0.3-1 mil may be used, and which may be referred to as thin dense chrome plating.
Chrome plating of wear parts generally includes a transition, or taper, between coated sections, regions, or features of the part and uncoated sections, regions, or features. The chrome plating may therefore be described as defining a coating profile that includes a region of uniform thickness plating and one or more regions where the plating tapers away from the region of uniform thickness to zero. These regions of tapered thickness may additionally or alternatively be referred to as run-out regions or run-off regions, and/or the plating may be described as having run-out or run-off. These regions of tapered thicknesses may be desired, so as to limit stress enhancement regions, to limit edge based wear, and to generally increase the fatigue life of the part.
Due to the tolerances, and sometimes critical tolerances, associated with mechanical assemblies that include wear parts, it is often desirable for replacement wear parts to have a coating profile that matches, as close as possible, if not exactly, the coating profile of the part being replaced. Differences in thicknesses of coatings and run-outs between a replacement part and a part being replaced of less than 0.5, or even less than 0.1, mils may be significant in some applications.